DURHAM — Durham police have found themselves dusting a lot of crime scenes lately, looking for fingerprints and evidence. Armed robbers have recently hit 16 restaurants and convenience stores -- and the attacks are becoming more violent.

Tuesday night, robbers struck again at the Academy Quick Stop off Chapel Boulevard in Durham. No one was seriously hurt, but police say the robbers have already shown they have no regard for human life.

Videotape from a camera behind the counter at the Academy Quick Stop shows two masked men, shoving a shotgun into the face of the store clerk and stealing the contents of the cash register.

"They already had the money and they shot for no reason. A bullet went through his neck on the left side," says Rehman.

"From the amount of force used here, this is totally different than anything that's occurred since July first," says Maj. Dwight Pettiford of theDurham Police Department.

Pettiford says the increased violence has police working hard to plot where the armed robbers will strike next. Police say 16 armed robberies have taken place in six weeks. The robberies have been concentrated along Chapel Hill Boulevard, Highway 55 and Highway 54 in Durham.

"Why are they choosing this particular area? If you look all over Durham there are business everywhere. Why are we clustered like this in this area," asks Pettiford.

Until the masked men are behind bars, Atta Rehman says standing behind the counter is a dangerous place to be.

Police say if you have to go to a convenience store late at night, be very careful and alert to who is around you.

The clerk who was shot in the neck Friday is in critical condition at Duke Hospital.

Police say there may be several groups of robbers committing the crimes.